1. Field of the Invention
The present invention relates to a shift switch control device for selection lever units of automatic transmissions and, more particularly, to a shift switch control device for selection lever units of sport mode-type automatic transmissions capable of selectively performing an automatic transmission mode or a manual transmission mode as desired, the shift switch control device designed to accomplish a reliable up-shift operation, so-called a xe2x80x9c+xe2x80x9d shift operation, and a reliable down-shift operation, so-called a xe2x80x9cxe2x88x92xe2x80x9d shift operation, during a manual transmission mode, and to be reduced in the number of its parts, thus being preferably simplified in its construction.
2. Description of the Prior Art
In recent years, sport mode-type automatic transmissions, designed to allow drivers to select an automatic transmission mode or a manual transmission mode as desired in accordance with driving conditions and/or driver""s tastes while driving, have been developed and proposed to be equipped within, particularly, a variety of expensive luxury cars.
Different from conventional transmissions with a fixed automatic transmission mode or a fixed manual transmission mode, such sport mode-type automatic transmissions allow drivers to enjoy the driving feeling to the full while selecting the automatic transmission mode or the manual transmission mode as desired in accordance with driving conditions and/or their tastes while driving their cars.
Such a sport mode-type automatic transmission is provided with a selection lever unit for allowing a driver to perform a desired shifting operation. The construction of a conventional selection lever unit for such sport mode-type automatic transmissions is shown in FIGS. 7, 8 and 9. As shown in the drawings, the conventional selection lever unit has a selection lever 100, which is installed within a main frame 111 and is used for selecting a desired mode or a desired range within a transmission pattern 110 having a manual transmission mode and an automatic transmission mode. A cable bracket 113 is connected to a shift cable (not shown) at a position around the selection lever 100. The above cable bracket 113 is operated in conjunction with the selection lever 100 when the automatic transmission mode is selected, thus actuating a transmission manual valve (not shown).
The selection lever 100 has two connection protrusions 114, while the cable bracket 113 has a connection lever 115 at a position corresponding to the connection protrusions 114. Therefore, the selection lever 100 is operated in conjunction with the cable bracket 113 through the engagement of the two connection protrusions 114 and 114xe2x80x2 with the connection lever 115 during an automatic transmission mode.
The conventional selection lever unit has a shift switch control device of FIG. 9. As shown in the drawing, the conventional shift switch control device for selection lever units comprises a manual mode select switch 103, an up-shift switch 101, a down-shift switch 102 and a switch actuation unit, which are provided on the top wall of the main frame 111. The up-shift switch 101 and the down-shift switch 102 are used for performing the up- and down-shifting operations when the manual transmission mode is selected by the selection lever 100.
In such a case, the up-shift switch 101 is positioned at the front portion of the shift switch control device, while the down-shift switch 102 is positioned at the rear portion of the control device. In addition, the manual mode select switch 103 is positioned between the up-shift switch 101 and the down-shift switch 102.
Two shift switch actuation members 104 and 105 are provided at positions corresponding to the up-shift switch 101 and the down-shift switch 102, with a gap defined between the two shift switch actuation members 104 and 105. When the manual transmission mode is selected by the selection lever 100, the lever 100 is inserted into the gap defined between the two shift switch actuation members 104 and 105 while pushing and turning on the manual mode select switch 103.
In each of the two shift switch actuation members 104 and 105, a tipping bar 108 is set within a housing 106 while being normally biased by a return spring 107 at its rear end, thus normally positioning the selection lever 100 at a neutral position.
Therefore, when the selection lever 100 is moved to perform a desired shifting operation, the tipping bars 108 of the two shift switch actuation members 104 and 105 actuate the up and down-shift switches 101 and 102, thus allowing the switches 101 and 102 to output up- and down-shifting signals.
In such a case, the manual mode select switch 103 is continuously operated by a side surface of the selection lever 100, thus being maintained at its activated state.
However, such a conventional shift switch control device for selection lever units of automatic transmissions is problematic in that it is very difficult to maintain the precise actuation gaps between the tipping bars 108 and the up- and down-shift switches 101 and 102. In addition, the operational direction of the tipping bars 108 is different from the operational direction of the up- and down-shift switches 101 and 102. Therefore, the shift switch control device may fail to accomplish a desired operational reliability.
In addition, it is very difficult to manufacture the tipping bars, and so the tipping bars are very expensive. Another problem experienced in the conventional shift switch control device resides in that it has a complex construction and is not easy to install within a limited area.
Accordingly, the present invention has been made keeping in mind the above problems occurring in the prior art, and an object of the present invention is to provide a shift switch control device for selection lever units of automatic transmissions capable of selectively performing an automatic transmission mode or a manual transmission mode as desired, which is designed to accomplish a reliable up-shift operation, so-called a xe2x80x9c+xe2x80x9d shift operation, and a reliable down-shift operation, so-called a xe2x80x9cxe2x88x92xe2x80x9d shift operation, during a manual transmission mode, and which is reduced in the number of its parts, thus being preferably simplified in its construction.
In order to accomplish the above object, the present invention provides a shift switch control device for selection lever units of automatic transmissions, comprising: a selection lever installed within a main frame of a chassis by a hinge shaft and used for selecting a desired range within a transmission pattern during an automatic transmission mode and performing an up- or down-shifting operation during a manual transmission mode, the transmission pattern having an automatic transmission mode pattern and a manual transmission mode pattern, the selection lever turning on or off up- and down-shift switches during the manual transmission mode, thus performing the up- or down-shifting operation; a rotary plate mounted to the hinge shaft at one side of the selection lever, with the up- and down-shift switches provided at the top end of the rotary plate while being spaced apart from each other at a predetermined gap, and a projection provided at the central portion of the rotary plate while extending toward the selection lever; a manipulation lever installed at the top portion of the selection lever such that the manipulation lever is positioned between the up- and down-shift switches at a M-stage of the manual transmission mode pattern, the manipulation lever being used for turning on or off the up- or down-shift switch; a projection guide plate provided on the selection lever at a position corresponding to the projection of the rotary plate under the manipulation lever, with an inclined surface formed at one end of the projection guide plate to prevent the up-shift switch from coming into undesired contact with the manipulation lever when the selection lever is moved from a D-stage to the M-stage, thus allowing the projection to push the rotary plate outward so as to position the manipulation lever in the gap between the up- and down-shift switches; and a rotary plate return means for giving an elastic returning force to the rotary plate, the rotary plate return means being mounted to the hinge shaft of the rotary plate at the outside of the rotary plate.
In the above shift switch control device, the M-stage of the manual transmission mode pattern has a plus (+) stage for actuating the up-shift switch and a minus (xe2x88x92) stage for actuating the down-shift switch.
In the preferred embodiment, the manipulation lever comprises: a horizontal part having a predetermined length so as to be free from coming into undesired contact with the up-shift switch when the selection lever is moved from the D-stage to the M-stage; and a vertical part extending from the tip of the horizontal part downward to a predetermined length so as to selectively come into contact with the up- and down-shift switches, thus turning on or off the up- and down-shift switches.
The projection guide plate comprises: the inclined surface formed at the end of the projection guide plate, the inclined surface being operated in conjunction with the projection of the rotary plate when the selection lever is moved from the D-stage to the M-stage, thus preventing the up-shift switch from coming into undesired contact with the manipulation lever; and a flat guide surface linearly guiding a movement of the projection when the selection lever at the M-stage performs an up- or down-shifting operation.
On the other hand, the return means comprises: a support bracket mounted to the hinge shaft of the rotary plate at the outside of the rotary plate; and a return spring positioned between the rotary plate and the support bracket.